wxSocket::Initialize() and Shutdown() are for main thread only.

Calling Initialize() from another thread could never work before but it wasn't
clear that this was the case so document it in the functions comments and
documentation now and add asserts checking that they are called from the main
thread only.

Also simplify the code as we don't actually need to do any reference-counting
here and a simple boolean flag indicating whether the sockets are initialized
is enough.

Closes #11119.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61985 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

diff --git a/include/wx/socket.h b/include/wx/socket.h
index e6b11b1f255f4f60fab40aa1f5d8cb4816bb882b..e978b5ca80169a4e6dc7717a3456a3bd96d0ace1 100644 (file)
--- a/include/wx/socket.h
+++ b/include/wx/socket.h
@@ -179,11 +179,21 @@ public:
     void SetNotify(wxSocketEventFlags flags);
     void Notify(bool notify);
 
-    // initialize/shutdown the sockets (usually called automatically)
-    static bool IsInitialized();
+    // initialize/shutdown the sockets (done automatically so there is no need
+    // to call these functions usually)
+    //
+    // should always be called from the main thread only so one of the cases
+    // where they should indeed be called explicitly is when the first wxSocket
+    // object in the application is created in a different thread
     static bool Initialize();
     static void Shutdown();
 
+    // check if wxSocket had been already initialized
+    //
+    // notice that this function should be only called from the main thread as
+    // otherwise it is inherently unsafe because Initialize/Shutdown() may be
+    // called concurrently with it in the main thread
+    static bool IsInitialized();
 
     // Implementation from now on
     // --------------------------
@@ -264,9 +274,6 @@ private:
     wxSocketEventFlags  m_eventmask;  // which events to notify?
     wxSocketEventFlags  m_eventsgot;  // collects events received in OnRequest()
 
-    // the initialization count, wxSocket is initialized if > 0
-    static size_t m_countInit;
-
 
     friend class wxSocketReadGuard;
     friend class wxSocketWriteGuard;

diff --git a/interface/wx/socket.h b/interface/wx/socket.h
index a0ada831198ac521cbe7c7a768cef749889a8b3d..b3b6837097a081b8fa8b4d20a5b15f698b6b255d 100644 (file)
--- a/interface/wx/socket.h
+++ b/interface/wx/socket.h
@@ -710,6 +710,8 @@ public:
         does anything) but you must call Shutdown() exactly once for every call
         to Initialize().
 
+        This function should only be called from the main thread.
+
         @return
             @true if the sockets can be used, @false if the initialization
             failed and sockets are not available at all.
@@ -721,6 +723,9 @@ public:
 
         This function undoes the call to Initialize() and must be called after
         every successful call to Initialize().
+
+        This function should only be called from the main thread, just as
+        Initialize().
      */
     static void Shutdown();
 

diff --git a/src/common/socket.cpp b/src/common/socket.cpp
index 7e1aafd4a200e82cd4ea6665fee8e28bf7669d2d..fb18c2e341b512a00a5caf152796a86769e75865 100644 (file)
--- a/src/common/socket.cpp
+++ b/src/common/socket.cpp
@@ -750,26 +750,33 @@ int wxSocketImpl::Write(const void *buffer, int size)
 // Initialization and shutdown
 // --------------------------------------------------------------------------
 
-// FIXME-MT: all this is MT-unsafe, of course, we should protect all accesses
-//           to m_countInit with a crit section
-size_t wxSocketBase::m_countInit = 0;
+namespace
+{
+
+// flag indicating whether wxSocketManager was already initialized
+bool gs_socketInitDone = false;
+
+} // anonymous namespace
 
 bool wxSocketBase::IsInitialized()
 {
-    return m_countInit > 0;
+    wxASSERT_MSG( wxIsMainThread(), "unsafe to call from other threads" );
+
+    return gs_socketInitDone;
 }
 
 bool wxSocketBase::Initialize()
 {
-    if ( !m_countInit++ )
+    wxCHECK_MSG( wxIsMainThread(), false,
+                 "must be called from the main thread" );
+
+    if ( !gs_socketInitDone )
     {
         wxSocketManager * const manager = wxSocketManager::Get();
         if ( !manager || !manager->OnInit() )
-        {
-            m_countInit--;
-
             return false;
-        }
+
+        gs_socketInitDone = true;
     }
 
     return true;
@@ -777,15 +784,16 @@ bool wxSocketBase::Initialize()
 
 void wxSocketBase::Shutdown()
 {
-    // we should be initialized
-    wxASSERT_MSG( m_countInit > 0, wxT("extra call to Shutdown()") );
-    if ( --m_countInit == 0 )
-    {
-        wxSocketManager * const manager = wxSocketManager::Get();
-        wxCHECK_RET( manager, "should have a socket manager" );
+    wxCHECK_RET( wxIsMainThread(), "must be called from the main thread" );
 
-        manager->OnExit();
-    }
+    wxCHECK_RET( gs_socketInitDone, "unnecessary call to Shutdown()" );
+
+    gs_socketInitDone = false;
+
+    wxSocketManager * const manager = wxSocketManager::Get();
+    wxCHECK_RET( manager, "should have a socket manager" );
+
+    manager->OnExit();
 }
 
 // --------------------------------------------------------------------------
@@ -821,13 +829,15 @@ void wxSocketBase::Init()
     m_eventmask    =
     m_eventsgot    = 0;
 
-    if ( !IsInitialized() )
+    // when we create the first socket in the main thread we initialize the
+    // OS-dependent socket stuff: notice that this means that the user code
+    // needs to call wxSocket::Initialize() itself if the first socket it
+    // creates is not created in the main thread
+    if ( wxIsMainThread() )
     {
-        // this Initialize() will be undone by wxSocketModule::OnExit(), all
-        // the other calls to it should be matched by a call to Shutdown()
-        if (!Initialize())
+        if ( !Initialize() )
         {
-            wxLogError("Cannot initialize wxSocketBase");
+            wxLogError(_("Cannot initialize sockets"));
         }
     }
 }